Each architectural framework (TOGAF, MODAF, DODAF, FEA) has its own development method that describes how to construct and deliver an architecture of the organisation from their prescribed artefacts. Perhaps it is just taken for granted that architects will research and use evidence where appropriate to justify their views and recommendations.  Yet  those methods i have used and have researched (i am not knowledgeable on all architecture methods) do not factor the concept of evidence application in their approach. So for principle 2 i am recommending that by adopting evidence based enterprise architecture it requires an addition to the governance and methodology to include activities that encourages research and application of evidence to support decisions, hypotheses and recommendations.